This application claims the benefit of Korean Patent Application No. 1999-3887, filed on Feb. 5, 1999, which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a liquid crystal display and a method of removing pattern defects thereof, more particularly, to a method of removing pattern defects (poor patterns) of a liquid crystal display having an IOP structure, where a transparent conductive layer is formed on a passivation layer.
2. Description of the Related Art
Data lines or active layers for liquid crystal display (hereinafter abbreviated LCD) are formed by depositing a conductive or semiconductor layer on an exposed surface of a substrate, then etching the deposited layer by photolithography. Residue may remain at an unwanted place if the layer is not properly patterned during photolithography. The residue of the conductive or semiconductor layer remaining as pattern defects (poor patterns) on the substrate may cause an electrical malfunction of the LCD. Therefore, an LCD in which pattern defects are removed after fabrication is typically used as a final product. Otherwise, LCDs which are unrepairable are wasted.
FIG. 1 shows a layout for explaining a method of removing pattern defects in an LCD according to a related art, and FIG. 2 is a cross-sectional view of the LCD bisected along with the cutting line Ixe2x80x94I in FIG. 1.
Referring to FIG. 1 and FIG. 2, a plurality of pixel cells are defined by the places where gate lines 11L and data lines 15L cross each other. A thin film transistor (hereinafter abbreviated TFT) and a pixel electrode 17 are formed in each pixel cell. A data signal transmitted through the data line 15L is transferred to the pixel electrode 17 by switching characteristics of TFT.
As shown in FIG. 2, a gate wire, including a gate electrode 11G and a gate line 11L, is formed on a substrate 100, and a gate insulating layer 12 covers an exposed surface of the substrate including the gate wire. An active layer 13, which follows along with the data line 15L, is formed on the gate insulating layer 12 over the gate electrode 11G.
A data wire is formed over the substrate including the active layer 13. The data wire consists of: the data line 15L crossing the gate line 11L to define a plurality of pixel cells; a source electrode 15S protruding out from the data line 15L; a drain electrode 15D standing face to face opposite the source electrode 15S, and a data pad 15P at the end of the data line 15L.
A passivation layer 16 covers an exposed surface of the structure, except for portions of the drain electrode 15D and data pad 15P. A pixel electrode 17 connected to the drain electrode 15D and a data covering layer 17P covering the data pad 15P are formed on the passivation layer 16.
In the above-structured LCD, pattern defects 101 and 102 may be generated, for example, when a portion of the active layer or data wire pattern remains at the site between the data line 15L and pixel electrode 17, or the space between the data pads 15P.
Remaining unwanted locations of electrically-conductive pattern defects generated from the active layer or data wire may degrade or impair the electrical function or performance of the LCD. Therefore, a process for removing the pattern defects is necessary.
One method of the related arts of removing pattern defects, is to irradiate a laser beam on a predetermined portion of the device. For instance, as shown in FIG. 2, an LCD is repaired by irradiating laser beams to the pattern defects 101 and 102 to be cut selectively. Namely, the passivation layer 16 and pattern defects 101 and 102 are removed by being irradiated by laser beams.
The method of removing pattern defects in an LCD according to the related art which uses laser, beams is effective provided that the pattern defects exist locally. Unfortunately, the related art is less effective when the sizes of the pattern defects are large, or when the pattern defects are distributed over a relatively large area and various places, because it takes a long time to remove them individually by laser beams. Moreover, wires near the pattern defects are damaged, when pinpoint laser irradiation is not expected, as each pattern defect must be irradiated by each laser beam.
Accordingly, the present invention is directed to a liquid crystal display, and a method of removing pattern defects thereof, that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a liquid crystal display and a method of removing pattern defects thereof which removes pattern defects in active layers or data wires of an LCD simultaneously and quickly, without causing any damage to other parts of the LCD. According to the invention, this object may be accomplished by exposing pattern defects in the air, then by carrying out an etching process using pixel electrodes and an etch-stop layer as an etch mask.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the present invention provides a method of removing pattern defects in a liquid crystal display, wherein the liquid crystal display comprises; a gate wire on a substrate, the gate wire including a gate electrode and gate line; a gate insulating layer covering an exposed surface of the substrate including the gate wire; a data wire on the gate insulating layer, the data wire including a data line, source electrode, and drain electrode; an active layer on the gate insulating layer, the active layer constituting a thin film transistor with gate, source, and drain electrodes which properly overlap one another; a passivation layer covering an exposed surface of the substrate except a portion of the data wire; and a pixel electrode on the passivation layer wherein the pixel electrode is connected to the exposed data wire. The method includes the steps of forming an etch-stop layer covering the data wire and thin film transistor, exposing at least one pattern defect by etching the passivation layer, using the etch-stop layer and pixel electrode as an etch mask, removing the pattern defect, and removing the etch-stop layer. The etch-stop layer also may be extended to cover the pixel electrode.
In another aspect, the present invention includes: a substrate; a gate wire on the substrate, the gate wire including a gate electrode and gate line; a gate insulating layer covering an exposed surface of the substrate, including the gate wire; a data wire on the gate insulating layer, the data wire including a data line, source electrode, and drain electrode; a thin film transistor connected electrically to the data line on the gate insulating layer, the thin film transistor including an active layer constituting a thin film transistor with gate, source, and drain electrodes which properly overlap one another; a pixel electrode connected to the drain electrode of the thin film transistor; and a passivation layer covering the data wire and thin film transistor except the drain electrode, wherein the passivation layer is covered by the pixel electrode and exposes the gate insulating layer except portions of the gate insulating layer where the data wire, thin film transistor, and pixel electrode are formed.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.